The present invention relates to a communication system for controlling terminal units through boundary scan elements, and particularly to a communication system which can quickly transmit output data from the terminal units.
A boundary scan test method has been proposed as one of the inspection methods with a plurality of IC chips arranged over a printed wire board with printed wiring formed thereon, to see whether or not connection between each IC chip and each printed wiring is properly made and whether or not each printed wiring is not broken.
This boundary scan test method can be applied to integrated circuits (IC chips) into which boundary scan elements are incorporated. The boundary scan element, for example as shown in FIG. 4, includes a plurality of boundary cells 114 individually provided between input/output terminals of an internal logic 111 for implementing the inherent functions of the integrated circuit 110 and input/output terminals 112/113 of the integrated circuit 110, a TAP controller (TAP circuit) 119 for controlling input and output of data to or from the boundary cells 114, a TDI terminal 120 for receiving test data, a TDO terminal 121 for transmitting test data, a TCK terminal 122 into which a clock signal is input, and a TMS terminal 123 for receiving a mode signal for switching the operation mode of the TAP controller 119; and, if required, it is further provided with a bypass register 115, an ID CODE register 116, an instruction register 117, a TRS terminal 124 for receiving a reset signal, or the like. In this connection, the bypass register 115 to instruction register 117 is referred to as boundary scan register (118).
To describe the respective terminals or the signals to be input/output through the respective terminals in detail, TDI (Test Data In) is a signal for serial-inputting instructions and data to a test logic, and is sampled at rising edges of TCK. TDO (Test Data Out) is a signal for serial-outputting data from the test logic, the output value being changed at falling edges of TCK. TCK (Test Clock) supplies a clock to the test logic. It is a dedicated input for enabling the use of a serial test data path independent of the system clock inherent to the component. TMS (Test Mode Select) is a signal for controlling the test operation, and is sampled at rising edges of TCK. The TAP controller decodes this signal. TRST (Test Reset) is a negative logic symbol for a synchronously initializing the TAP controller, and is optional.
The integrated circuit 110 into which such boundary scan element is incorporated can be tested on the operating state thereof and the connecting relationship between this integrated circuit 110 and external devices, by the procedures described below.
First, in checking the quality of the internal logic 111 of the integrated circuit 110, serial data (test data) are input to the TDI terminal 120 of the integrated circuit 110 as they are shifted, and thereby the test data are set into the respective boundary cells 114 corresponding to the respective input terminals 112. In this state, the integrated circuit 110 is operated before the data set in the respective boundary cells 114 corresponding to the respective output terminals 113 are shifted for output from the TDO terminal 121, and, on the basis of the corresponding relationship between the serial data (test result data) thus obtained and the test data input to this integrated circuit 110, the internal logic 111 of the integrated circuit 110 is tested for its quality.
The boundary scan test method can also be carried out on a plurality of integrated circuits as long as the boundary scan elements are incorporated therein.
For example, a plurality of integrated circuits 110 mounted on a substrate 126 as shown in FIG. 5 can also be subjected to a test for breakage and the like of the printed patterns between the integrated circuits 110, along with a test on the integrated circuits 110 themselves.
In this case, the respective boundary scan elements incorporated in the plurality of integrated circuits 110 are connected in series with each other. Specifically, the TDO terminal 121 of the first integrated circuit 110 (the left in the drawing) and the TDI terminal 120 of the second integrated circuit 110 (the right in the drawing) are connected with each other, the output terminal 129 of a boundary scan controller board 128 provided in host computer unit 127 or the like and the TDI terminal 120 of the first integrated circuit 110 are connected with each other, and the input terminal 130 of the boundary scan controller board 128 and the TDO terminal 121 of the second integrated circuit 110 are connected with each other. The test procedures are as follows:
In testing breakage, short circuit, and the like of the printed patterns, a test data preparing tool 131 or the like is used to prepare test data (serial data), which is output from the output terminal 129 of the boundary scan controller board 128 and is input to the TDI terminal 120 of the first integrated circuit 110 while shifted, setting the test data into the respective boundary cells 114 corresponding to the respective output terminals 113 in this integrated circuit 110. In this state, the data stored in these respective boundary cells 114 are output from the respective output terminals 113 provided in the first integrated circuit 110 as shown in FIG. 6, and are input through the respective printed patterns 133 constituting a system bus and the like to the respective input terminals 112 of the second integrated circuit 110, and further fetched into the respective boundary cells 114 corresponding to these respective input terminals 112.
Thereafter, the data stored in the respective boundary cells 114 of these respective integrated circuits 110 are shifted and fetched through the input terminal 130 of the boundary scan controller board 128 as they are analyzed by using a test result analyzing tool 132 or the like, so that a test can be made for breakage, short circuit, and the like in such a test range 135 as the printed patterns 133 providing connection between the integrated circuits 110.
Next, in inspecting the internal logic 111 of the respective integrated circuits 110, test data are output from the output terminal 129 of the boundary scan controller board 128, and are input to the TDI terminal 120 of the first integrated circuit 110 as they are shifted, so as to be set into the respective boundary cells 114 corresponding to the respective input terminals 112 of this integrated circuit 110 as shown in FIG. 8.
Subsequently, this integrated circuit 110 is operated, and the resulting data are fetched into the respective boundary cells 114 corresponding to the respective output terminals 113 before the data stored in these respective boundary cells 114 are shifted to be output from the TDO terminal 121 of the first integrated circuit 110. Here, the second integrated circuit 110 is brought into a bypass state as shown in FIG. 7 by the boundary scan controller board 128, so that the data output from the TDO terminal 121 are bypassed through the second integrated circuit 110 and fetched through the input terminal 130 of the boundary scan controller board 128. Then, the test analyzing tool 132 or the like can be used for analysis of the fetched data to test whether or not the first integrated circuit 110 operates properly.
Next, in the cases of inspecting the second integrated circuit 110, the boundary scan controller board 128 similarly brings the first integrated circuit 110 into a bypass state as shown in FIG. 7 before test data are output from the output terminal 129 of the boundary scan controller board 128 and bypassed through the first integrated circuit 110. Then, the test data are input to the TDI terminal 120 of the second integrated circuit 110 while shifted, to be set into the respective boundary cells 114 corresponding to the respective input terminals 112 of this integrated circuit 110 as shown in FIG. 8. Subsequently, this integrated circuit 110 is operated, and the resulting data are fetched into the respective boundary cells 114 corresponding to the respective output terminals 113. Thereafter, the data stored in the respective boundary cells 114 are shifted to be output from the TDO terminal 121, and further fetched through the input terminal 130 of the boundary scan controller board 128. Then, the fetched data can be analyzed by using the test result analyzing tool 132 and the like, so as to test whether or not the second integrated circuit 110 operates properly.
In this way, a substrate 126, as long as using integrated circuits 110 into which boundary scanning circuits are incorporated, can be tested for the quality of the respective integrated circuits 110 themselves and the connecting relationship between the integrated circuits 110 and the like by conducting the boundary scan test method.
Now, it was found by the present inventor that when integrated circuits into which such boundary scan elements are incorporated are used to constitute the substrate or the like of a sensor module, input and output of serial data can be made to or from the respective integrated circuits mounted on the substrate 126 at a rate on the order of 20 Mbps without the use of communication integrated circuits or the like.
Then, a communication system was proposed which applies the boundary scan elements to carry out communication with host computer units and the like without the use of communication devices.
FIG. 9 is a block diagram showing an example of the communication system to which the boundary scan elements are applied.
The communication system 140 shown in this figure includes: a communication controller device 141 for carrying out the transmitting of control data, the collection of detected data, and the like; a plurality of sensor units 142a-142c for carrying out the monitoring of an object to be monitored; a plurality of boundary scan elements 143a-143c provided for each of these sensor units 142a-142c, the boundary scan elements carrying out such processing as fetching the control data output from the aforesaid communication controller device 141 to supply the same to the respective sensor units 142a-142c, and fetching the detected data or the like output from these respective sensor units 142a-142c to supply the same to the aforesaid communication controller device 141; and communication lines 144 for providing connection between each of these boundary scan elements 143a-143c and the aforesaid communication controller device 141. The boundary scan elements are connected in series to the communication controller device 141. Specifically, the connection is made in such a manner that the output terminal 141a of the communication controller device 141 is connected to the TDI terminal of the boundary scan element 143a, the TDO terminal of the boundary scan element 143a connected to the TDI terminal of the next boundary scan element 143b, and so on, and the TDO terminal of the boundary scan element 143c is connected to the input terminal 141b of the communication controller device 141.
The function of this communication system 140 is as follows:
The respective boundary scan elements 143a-143c function in synchronization with the clock signal transmitted from the TCK terminal 141d of the communication controller device 141, and the operation mode of each TAP controller is switched by the TMS signal transmitted from the TMS terminal 141c of the communication controller device 141.
Now, in driving the respective sensor units 142a-142c according to the instruction from the host computer unit 145, control data (serial data) are output from the output terminal 141a of the communication controller device 141, and they are supplied to the respective boundary scan elements 143a-143c and set into the boundary cells corresponding to the output terminals. Then, the control data set are output from the output terminals, and supplied to the respective sensor units 142a-142c corresponding to the respective boundary scan elements 143a-143c, thereby driving these units.
Moreover, in the cases of collecting the detected data from the respective sensor units 142a-142c according to the instruction from the host computer unit 145, the detected data of the respective sensor units 142a-142c are once set in the respective boundary cells corresponding to the input terminals of the corresponding, respective boundary scan elements 143a-143c. Then, they are output as serial data from the TDO terminals, and fetched through the input terminal 141b of the communication controller device 141.
Such communication system 140, when setting control data into the respective boundary scan elements 143a-143c or when outputting the detected data from the respective boundary scan elements 143a-143c, can be maximized to 20 Mbps in data transfer rate, thereby allowing the transfer of communication data at higher rates than those of conventional communication systems.
However, the communication system described above had a problem in that when the detected data of the terminal units such as sensor units connected to the boundary scan elements are enormous, e.g. picture signals and the like, a drop in the transfer rate is undeniable and the effect of the high-rate data transfer obtained by the application of the boundary scan elements as communication elements is not exerted sufficiently.
Moreover, since the boundary scan elements can only input and output information in the form of digital signals, there was a problem in that they cannot fetch information in an analog signal form.
An object of the present invention is to provide a communication system which can transfer data from terminal units at higher rates.
Another object of the present invention is to provide a communication system which can transfer analog signals from terminal units at higher rates.
According to the present invention, there is provided a communication system comprising: a plurality of boundary scan elements including a plurality of boundary cells individually assigned to respective input terminals and output terminals, a TAP circuit for controlling input and output of data to or from the aforesaid boundary cells, a TDI terminal for inputting serial data to be supplied to the aforesaid boundary cells, a TDO terminal for outputting data from the aforesaid boundary cells in the form of serial data, a TCK terminal into which a clock signal is input, and a TMS terminal into which a mode signal for switching the operation mode of the aforesaid TAP circuit is input; a plurality of terminal units each connected with each of the aforesaid boundary scan elements or provided with an IC into which each of the elements is incorporated; and a communication controller connected with the aforesaid boundary scan elements in series for transmitting/receiving through the aforesaid boundary scan elements control data for individually controlling the aforesaid terminal units, wherein the aforesaid terminal units are connected in parallel and a single data communication line for transmitting output data of the aforesaid terminal units to the aforesaid communication controller is provided.
In the present invention, the communication controller controls the terminal units by transmitting control data thereto through the boundary scan elements. Then, data obtained by the terminal units are directly transmitted to the communication controller through the data communication line without the intermediary of the boundary scan elements.
This enables the high-rate transfer of data even when the output data of the terminal units are enormous, and allows the transfer of the output data even when they are analog signals.
Moreover, the output data are transmitted through a single data communication line, so that wiring of the system is simplified. In addition, the boundary scan elements are driven synchronously, so that when the respective terminal units are switched to transmit their output data through the data communication line, little time rag is produced between the output data and interference therebetween is avoided.
In the present invention, the terminal units include various sensor units, such as monitoring camera units, and the output data include the detected data of the sensor units, such as moving picture signals and still picture signals.
The control data include not only the data to be transmitted to the terminal units for the control of the terminal units, but also the status data and the like of the terminal units to be transmitted back from the terminal units.
The boundary scan elements include not only independent, separate packages but also those incorporated in other ICs. Besides, the input terminals and output terminals represent, in the case where each of the boundary scan elements is an independent package, the input terminals and output terminals thereof, and represent, in the case where the boundary scan elements are incorporated into other ICs, the input terminals and output terminals of the ICs. Then, the aforesaid output terminals and the aforesaid input terminals are connected to the input terminals and the output terminals of the terminal units, respectively, so that the data of the boundary cells are output to the terminal units and data are conversely input to the boundary cells.
Moreover, according to the present invention, the communication system described above may be provided in which: the output data are analog signals; and an analog signal processor for processing the output data may be provided between the communication controller and the communication liner. In this invention, the provision of the aforesaid analog signal processor can ease the load on the communication controller to quickly perform the processing of analog signals.
Furthermore, according to the present invention, there is provided the above-described communication system in which: the boundary cells include a plurality of input-terminal-side boundary cells connected in series and assigned to the respective input terminals individually, and a plurality of output-terminal-side boundary cells connected in series and assigned to the respective output terminals individually; and the input-terminal-side boundary cells and the aforesaid output-terminal-side boundary cells are connected in parallel between the TDI terminal and the TDO terminal.
In this invention, the boundary cells are not coupled all in series as conventionally, but are divided into the input-terminal-side boundary cells assigned to the input terminals and the output-terminal-side boundary cells assigned to the output terminals, which are connected in parallel between the TDI terminal and the TDO terminal. Accordingly, for example, when data from the TDI terminal are being set into the output-side boundary cells, direct transfer of the data to the output-side boundary cells can be made without the intermediary of the aforesaid input-terminal-side boundary cells, which can further realize the higher-rate transfer of data between the boundary scan elements and the communication controller or the terminal units.